Depletion of reduction potential and key energy generation metabolic enzymes underlies tellurite toxicity in Deinococcus radiodurans

Abstract

Oxidative stress resistant Deinococcus radiodurans surprisingly exhibited moderate sensitivity to tellurite induced oxidative stress (LD50 = 40 μM tellurite, 40 min exposure). The organism reduced 70% of 40 μM potassium tellurite within 5 h. Tellurite exposure significantly modulated cellular redox status. The level of ROS and protein carbonyl contents increased while the cellular reduction potential substantially decreased following tellurite exposure. Cellular thiols levels initially increased (within 30 min) of tellurite exposure but decreased at later time points. At proteome level, tellurite resistance proteins (TerB and TerD), tellurite reducing enzymes (pyruvate dehydrogense subunits E1 and E3), ROS detoxification enzymes (superoxide dismutase and thioredoxin reductase), and protein folding chaperones (DnaK, EF-Ts, and PPIase) displayed increased abundance in tellurite-stressed cells. However, remarkably decreased levels of key metabolic enzymes (aconitase, transketolase, 3-hydroxy acyl-CoA dehydrogenase, acyl-CoA dehydrogenase, electron transfer flavoprotein alpha, and beta) involved in carbon and energy metabolism were observed upon tellurite stress. The results demonstrate that depletion of reduction potential in intensive tellurite reduction with impaired energy metabolism lead to tellurite toxicity in D. radiodurans.

Involvement of phosphoesterases in tributyl phosphate degradation in Sphingobium sp. strain RSMS

“…Destaining, reduction, alkylation and in-gel trypsin digestion of the excised gel plugs and elution of oligopeptides and cocrystalization with CHCA matrix were performed as described earlier (Anaganti et al 2014). The oligopeptide samples were analysed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (UltraFlex III MALDI ToF/ToF mass spectrometer, Bruker Daltonics, Germany) in MS mode, as per the manufacturer's instructions and exactly as per the calibration and spectral acquisition protocol described earlier (Panda et al 2014).…”

“…The proteins were applied to 3-10 NL IPG strips, 17 cm (BioRad, India), by cup-loading method, as per the manufacturer's instructions and as detailed earlier (Anaganti et al 2014;Panda et al 2014). Second dimensional resolution was achieved by 14 % SDS-PAGE.…”

DNA adenine hypomethylation leads to metabolic rewiring in Deinococcus radiodurans

“…Treatment of protein gel plugs for destaining, reduction, alkylation, in-gel trypsin digestion and elution of oligopeptides was exactly as described earlier [22]. One hundred proteins were identified by mass spectrometry using UltraFlex III MALDI-TOF/TOF mass spectrometer (Bruker Daltonics, Germany).…”

“…The 2D electrophoresis was carried out as reported earlier [15,22]. In brief, cellular proteins (300 μg) were resolved by iso-electric focusing (pH 4-7, 11 cm IPG strips, BioRad, India) using cup loading method followed by 10% SDS-PAGE.…”

Accumulation of heme biosynthetic intermediates contributes to the antibacterial action of the metalloid tellurite

“…The current hypothesis of tellurite toxicity in bacteria is based on observations that tellurite depletes thiols14, which alters the reduction potential of the cell15, and elicits the production of reactive oxygen species (ROS) and ROS-detoxifying enzymes1617. This hypothesis proposes that the main causes of tellurite toxicity is its oxidant nature11.…”